/*
 *	TCircularBuffer.java
 *
 *	This file is part of Tritonus: http://www.tritonus.org/
 */

/*
 *  Copyright (c) 1999 by Matthias Pfisterer
 *
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Library General Public License as published
 *   by the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU Library General Public License for more details.
 *
 *   You should have received a copy of the GNU Library General Public
 *   License along with this program; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

/*
|<---            this code is formatted to fit into 80 columns             --->|
*/

package org.tritonus.share;

import org.tritonus.share.TDebug;

public class TCircularBuffer {
	private boolean m_bBlockingRead;
	private boolean m_bBlockingWrite;
	private byte[] m_abData;
	private int m_nSize;
	private long m_lReadPos;
	private long m_lWritePos;
	private Trigger m_trigger;
	private boolean m_bOpen;

	public TCircularBuffer(int nSize, boolean bBlockingRead, boolean bBlockingWrite, Trigger trigger) {
		m_bBlockingRead = bBlockingRead;
		m_bBlockingWrite = bBlockingWrite;
		m_nSize = nSize;
		m_abData = new byte[m_nSize];
		m_lReadPos = 0;
		m_lWritePos = 0;
		m_trigger = trigger;
		m_bOpen = true;
	}

	public void close() {
		m_bOpen = false;
		// TODO: call notify() ?
	}

	private boolean isOpen() {
		return m_bOpen;
	}

	public int availableRead() {
		return (int) (m_lWritePos - m_lReadPos);
	}

	public int availableWrite() {
		return m_nSize - availableRead();
	}

	private int getReadPos() {
		return (int) (m_lReadPos % m_nSize);
	}

	private int getWritePos() {
		return (int) (m_lWritePos % m_nSize);
	}

	public int read(byte[] abData) {
		return read(abData, 0, abData.length);
	}

	public int read(byte[] abData, int nOffset, int nLength) {
		if (TDebug.TraceCircularBuffer) {
			TDebug.out(">TCircularBuffer.read(): called.");
			dumpInternalState();
		}
		if (!isOpen()) {
			if (availableRead() > 0) {
				nLength = Math.min(nLength, availableRead());
				if (TDebug.TraceCircularBuffer) {
					TDebug.out("reading rest in closed buffer, length: " + nLength);
				}
			} else {
				if (TDebug.TraceCircularBuffer) {
					TDebug.out("< not open. returning -1.");
				}
				return -1;
			}
		}
		synchronized (this) {
			if (m_trigger != null && availableRead() < nLength) {
				if (TDebug.TraceCircularBuffer) {
					TDebug.out("executing trigger.");
				}
				m_trigger.execute();
			}
			if (!m_bBlockingRead) {
				nLength = Math.min(availableRead(), nLength);
			}
			int nRemainingBytes = nLength;
			while (nRemainingBytes > 0) {
				while (availableRead() == 0) {
					try {
						wait();
					} catch (InterruptedException e) {
						if (TDebug.TraceAllExceptions) {
							TDebug.out(e);
						}
					}
				}
				int nAvailable = Math.min(availableRead(), nRemainingBytes);
				while (nAvailable > 0) {
					int nToRead = Math.min(nAvailable, m_nSize - getReadPos());
					System.arraycopy(m_abData, getReadPos(), abData, nOffset, nToRead);
					m_lReadPos += nToRead;
					nOffset += nToRead;
					nAvailable -= nToRead;
					nRemainingBytes -= nToRead;
				}
				notifyAll();
			}
			if (TDebug.TraceCircularBuffer) {
				TDebug.out("After read:");
				dumpInternalState();
				TDebug.out("< completed. Read " + nLength + " bytes");
			}
			return nLength;
		}
	}

	public int write(byte[] abData) {
		return write(abData, 0, abData.length);
	}

	public int write(byte[] abData, int nOffset, int nLength) {
		if (TDebug.TraceCircularBuffer) {
			TDebug.out(">TCircularBuffer.write(): called; nLength: " + nLength);
			dumpInternalState();
		}
		synchronized (this) {
			if (TDebug.TraceCircularBuffer) {
				TDebug.out("entered synchronized block.");
			}
			if (!m_bBlockingWrite) {
				nLength = Math.min(availableWrite(), nLength);
			}
			int nRemainingBytes = nLength;
			while (nRemainingBytes > 0) {
				while (availableWrite() == 0) {
					try {
						wait();
					} catch (InterruptedException e) {
						if (TDebug.TraceAllExceptions) {
							TDebug.out(e);
						}
					}
				}
				int nAvailable = Math.min(availableWrite(), nRemainingBytes);
				while (nAvailable > 0) {
					int nToWrite = Math.min(nAvailable, m_nSize - getWritePos());
					// TDebug.out("src buf size= " + abData.length + ", offset = " + nOffset + ", dst buf size=" + m_abData.length + " write pos=" + getWritePos() + " len=" + nToWrite);
					System.arraycopy(abData, nOffset, m_abData, getWritePos(), nToWrite);
					m_lWritePos += nToWrite;
					nOffset += nToWrite;
					nAvailable -= nToWrite;
					nRemainingBytes -= nToWrite;
				}
				notifyAll();
			}
			if (TDebug.TraceCircularBuffer) {
				TDebug.out("After write:");
				dumpInternalState();
				TDebug.out("< completed. Wrote " + nLength + " bytes");
			}
			return nLength;
		}
	}

	private void dumpInternalState() {
		TDebug.out("m_lReadPos  = " + m_lReadPos + " ^= " + getReadPos());
		TDebug.out("m_lWritePos = " + m_lWritePos + " ^= " + getWritePos());
		TDebug.out("availableRead()  = " + availableRead());
		TDebug.out("availableWrite() = " + availableWrite());
	}

	public static interface Trigger {
		public void execute();
	}

}

/*** TCircularBuffer.java ***/
